Abstract

Objective: High and low body mass index (BMI) values and inaccurate body weight perceptions (BWP) (i.e.: mismatch between BMI and BWP) are known risk factors for depression/suicide. However, the relationships between BMI, BWP and depression are still insufficiently understood in adolescents, and data are lacking concerning the entire range of BMI in either gender. This study aimed to investigate how BMI and BWP are related to depression in adolescents, exploring the entire range of BMI in both genders.

Method: Observational cross-sectional survey of a representative sample adolescents aged 17 from metropolitan France. A total of 39,542 subjects responded to a self-administered questionnaire between March 15th and March 31st 2008. They were classified according to their BMI (WHO thresholds: underweight/normal/overweight or obese), their BWP (five response choices from "too thin" to "too fat") and their depression levels (measured with the Adolescent Depression Rating Scale).

Depression scores were calculated for each group defined by crossing the 4 classes of BMI and the 5 categories of BWP. The interaction between BMI, BWP and depression was investigated using variance analysis. Results were secondarily adjusted to control for home environment and socioeconomic status. Analyses were performed separately for boys and girls.

Results: An interaction was observed between BMI, BWP and depression. Irrespective of BMI and gender, adolescents who felt they were almost the right weight had low depression scores. The greater the discrepancy between BMI and BWP, the more likely were adolescents to show high depression scores.

Conclusions: From a clinical perspective, asking adolescents about their BWP could help to better identify those at risk for depression.